An overhead view displaying device is known in which the entire surroundings of a vehicle is photographed by a plurality of cameras and a captured image acquired from each camera is transformed into an overhead view image, and a composite image that is synthesized from a plurality of the overhead view images are displayed on a monitor, so that the driver or others can visually recognize conditions around the vehicle. In such an overhead view displaying device, it is necessary to precisely align the overhead view images with each other. Therefore, it is required to calibrate installation states of the cameras, e.g. installation positions and installation angles of the cameras with a high accuracy. In PTL1, a camera adjusting device is disclosed in which it is determined whether calibration markers that are arranged at predetermined points around the vehicle are correctly photographed or not, and if it is determined that they are not correctly photographed, states of incorrect calibration markers are output and also measures for correction are output and guided.